The invention relates to a method for recognizing the knocking of an internal-combustion engine and to a device for carrying out the method.
It is known that so-called knocking can occur under specific operating conditions of an internal-combustion engine. By this is meant shock waves of a fuel/air mixture which become noticeable as, inter alia, audio-frequency vibrations of the engine. Since the knocking is accompanied, as a rule, by a high thermal load on the piston-cylinder wall located on the combustion-space side, during which erosions of material can occur, the aim is fundamentally to prevent knocking, since, if it occurs for a relatively long period of time, it can lead to a destruction of the internal-combustion engine.
However, since, on the other hand, the aim is to utilize as far as possible the existing working range of the internal-combustion engine, particularly with regard to engines for racing cars, there is a need to recognize the knocking of the internal-combustion engine as early and as reliably as possible. At the same time, there is the measurement problem of reading out the knock signal reliably and in a fault-free manner from the vibrations of the internal-combustion engine recorded by a sensor, so that the internal-combustion engine can be regulated appropriately as a function of the occurrence of the knocking.
It is generally known that, to recognize knocking, a signal assigned to the knocking process is compared with a reference signal. If the reference signal is exceeded by the knock signal, a knock-recognition signal is transmitted. A disadvantage of this is that the reference signal has to be provided in a highly complicated manner.